My mum thinks it's inappropriate living with my not actual dad?

I've known my dad who raised me isn't actually my real dad for a year now, and I'm in my late teens. My mum is the one who told me, now my mum and dad have been divorced since I was a child and my dad has been the one raising me for nearly all of my life. My mum has always tried to get me to live with her, she even tried blackmailing me a few times and getting the courts involved. She is an alcoholic and a smoker, jobless for decades and lives in a shitty apartment. I live with my dad who has a nice house and is a non-drinker and smoker, and is more stable than my mother.

But because she told me my dad isn't my blood related dad she says he has nothing to do with me and isn't my family, I told her she's saying bullshit then she tells me it's inappropriate to live with him because he isn't related to me. I think she's fucking stupid and is only saying this because she wants me to live with her, I think she is a psycho and she is disgusting for even saying that.

I have never met my actual dad, and I still consider the one who raised me to be my dad. I find it very gross for my mum saying it's inappropriate, like I'm going to date him or something, why? He's literally like 50 years old, I would never date him because he's my dad. I got really angry at my mum and told her he's still my dad, but she keeps saying it doesn't matter if he raised me. How do I tell my mum to fuck off?